Massachusetts is set to adopt a first of its kind equal pay law – one that it’s supporters are lauding as the most thorough in the nation.

The law, signed by the Republican governor, Charlie Baker, on Monday after it unanimously passed the state legislature, will make it illegal for employers to inquire about salary or wage history. However, employees will be able to share their salary history if they choose to. Massachusetts is the first US state to bar inquiries into salary history.

The law is intended to break the pattern of unequal pay for women in the workforce, since employers will no longer be encouraged to low-ball female employees in negotiations who may have been paid unequally in their previous jobs.

“For too many generations women have done equally hard, equally skilled, and equally responsible work as men in the same workplace,” said state senator Pat Jehlen, one of the bill’s backers in a statement. “This is an important milestone on the journey toward equity for women and families all across this Commonwealth.”

Supporters cite a study which shows women in the state still earn 82 cents for every dollar earned by their male peers, despite the fact that Massachusetts was the first in the nation to adopt an equal pay law more than 60 years ago, nine years before the first federal legislation was passed.

“This is the Commonwealth of Mass that in 1954 passed the first legislation around gender discrimination, and I think it’s incredibly apt that we would be one of the first states here today to pass legislation to ensure that people are paid what they are worth,” Baker told reporters after signing the bill.

Elise Gould, a senior economist with the Economic Policy Institute, says that while in general the path toward equal pay involves transparency between employer and employee, the new Massachusetts provisions are counterintuitive.

“It essentially acknowledges that employers hold information about wages within their firm they don’t have to share, and says that a worker should be able to withhold personal information about their earning history,” said Gould. “If there is a history of racial or gender discrimination, it would be perpetuated by requiring an applicant to disclose their salary information.”

That new law, which requires “that an employee refrain from inquiring about, discussing or disclosing information about either the employee’s own wages, or about any other employee’s wages” also will also change the way employees are allowed to share salary information among themselves.

Under the law, which will go into effect in July 2018, employers will not be allowed to bar employees from sharing salary information with fellow colleagues.

It will also make Massachusetts the one of a few states including California and New York to pass a “comparable work” law, giving leverage to employees who may try to sue their employers over unequal pay.

According to the new law, “a job title or job description alone shall not determine comparability”. Rather, skill sets and working conditions set the bar for whether work is comparable.

“I have been trying to get this bill passed since Senator Jehlen first filed it in 1998,” said Representative Ellen Story, a Democrat, in a statement. “But, there are some who have been waiting even longer.”

Dorothy Simonelli, 83, a former cafeteria worker at Everett high school, also attended the bill signing, according to Masslive. In 1989, Simonelli and her fellow cafeteria workers sued the school after they were denied a raise, despite janitors earning a higher salary. They won the suit, but the supreme judicial court overturned the ruling in 1998, after deciding that the positions were not comparable.

“There are no words,” Simonelli, told Masslive. “I just feel so wonderful. I’m so happy for my co-workers and all the ones that have passed on.”

The new bill will also protect companies from lawsuits for three years if they are already running self evaluations and are working to correct wage gaps on their own.